System for comminuting refuse



Dec. 21, 1965 N. A. PERSON SYSTEM FOR COMMINUTING REFUSE 2 Sheets-Sheet1 Filed April 6. 1961 .III/

F'iET-Z INVENTOR. IVOQMA/V A0 P/Z-ew/v Dec. 21, 1965 N. A. PIERSONSYSTEM FOR COMMINU'I'ING REFUSE 2 Sheets-Sheet 2 Filed April 6. 1961 mumFUEL-'7 F.LET'E INVENTOR. A/OQMA/V A, PIE-z so/v F iIE.-4

QZZZ United States Patent 3,224,839 SYSTEM FOR COMMINUTING REFUSE NormanA. Pierson, R0. Box 755, Norman, Okla. Filed Apr. 6, 1961, Ser. No.101,188 13 Claims. (Cl. 23-259.]l)

This invention relates to a system for reducing the average particlesize of a mixture of heterogeneous materials. More particularly, but notby way of limitation, the present invention relates to a system forpulverizing and grinding municipal refuse and analogous waste materials.

In the process of preparing a beneficial compost from municipal refuseby bacterial decomposition, it is necessary to treat the raw refuse inseveral ways prior to subjecting it to bacterial digestion in the finalcomposting operation. Thus, the refuse must be homogenized and adjustedin moisture content prior to charging it to the digesting cells. Inhomogenizing the refuse, the refuse must be brought to a relativelyuniform particle size, which particle size is substantially lower thanthe average particle size occurring in the raw refuse. Since the rawrefuse, that is, the refuse in the form in which it is collectedthroughout the municipality, may contain relatively large and hardobjects such as boards, pieces of sheet metal and chunks of glass aswell as relatively small particulate matter and liquids, the problem ofpulverizing or reducing the particle size of such a heterogeneous massis one which requires special equipment. Such equipment must be capableof reducing the particle size of such objects as steel plates and panelsof glass while also effectively functioning to reduce the particle sizeof relatively soft material such as cardboard boxes, newspapers,grapefruit rinds and the like.

The present invention contemplates a novel system for comminutingmunicipal refuse which, in its broadest and most basic aspect, comprisesa large pulverizing device for effecting an initial particle sizereduction in which the large, bulky, relatively hard materials are thosewhich are primarily affected, a metering device for classifyingaccording to particle size the material discharged from the pulverizingdevice, and a chain grinder for effecting the final particle sizereduction and homogenization.

The pulverizing device comprises a large, horizontally mounted,rotatable drum having, in a preferred embodiment, a plurality oftriangular-shaped blades mounted on the inner periphery of the drum forpuncturing cans and cutting metal plates, fracturing glass, andotherwise, grinding, cutting and tearing large, bulky or hard objectsinto smaller pieces. The raw refuse material is fed into the pulverizingdrum by means of a series of sweep blades located at the intake end ofthe drum and pitched with respect to the axis of rotation of the drum sothat refuse fed into the drum is forced by the sweep blades into theinterior of the drum. Similar sweep blades are located adjacent thedischarge end of the drum so that material inside the drum which hasbeen subjected to the action of the blades is swept out of the dischargeend of the drum.

At the discharge end of the pulverizing device, a novel metering deviceis secured to the drum for rotation therewith and functions to classifythe pulverized material discharged from the drum according to particlesize. The metering device is constructed to allow the pulverized refusewhich is of relatively smaller particle size to be discharged laterallyfrom the metering device at a point which is closer to the drum than thepoint of discharge of those particles which are of relatively largerparticle size. In other words, the latter particles are dischargedlaterally from the metering device at a point which is further removedfrom the discharge end of the drum in a direction measured along theaxis of rotation of the drum.

Materials which have not been effectively pulverized by the bladeswithin the drum, and which therefore remain of a size too large to bedischarged laterally from the metering device, are passed through themetering device and discharged from one end thereof. At this point theyare picked up by a suitable conveyor system and recycled to the intakeend of the pulverizing drum.

The third major element of the system of the present invention is thechain grinding device which is located to one side of the meteringdevice for receiving the lateral discharge of classified pulverizedrefuse therefrom. The chain grinder is oriented with respect to themetering device so that the particles of smaller size which arelaterally discharged by the metering device are caused to enter thechain grinder at a point intermediate its length. Larger particlesdischarged from the metering device enter the end portion of the chaingrinder and thus travel farther through the chain grinder than thesmaller particles. They are therefore subjected to a substantiallygreater amount of grinding action than the smaller particles enteringthe grinder intermediate its length.

By virtue of this arrangement of the large pulverizing drum, themetering device and the chain grinder, along with the associatedconveyor system for recycling certain materials through the pulverizingdevice, overloading of the chain grinder at any time is avoided.Moreover, the comminution of such difiicultly grindable objects asrocks, tree limbs, metal plates, tin cans and bedsprings is effectivelyaccomplished. The position of the grinder to one side of the meteringdevice and pulverizing drum allows the comminuting system to becompactly and economically constructed. Also, in recycling a portion ofthe refuse discharged from the pulverizing drum back through the drumfor one or more additional passes, incoming raw refuse may be partiallyinoculated with bacteria and spores which have had an opportunity fordevelopment and growth during the passage of the recycled refuse throughthe pulverizing drum and over the recycling conveyors. The recyclingsystem also affords an opportunity to add a suitable inoculant to therecycled refuse material so that an enriched bacteria and fungus contentmay be developed in the refuse being comminuted in the system.

From the foregoing, it will be perceived that one of the importantobjects of this invention is to provide a comminuting system which iscapable of effecting a substantial reduction in the average particlesize of a mass of heterogeneous materials.

A further object of the present invention is to provide a comminutingsystem for utilization in homogenizing a mass of municipal refuse, whichsystem, by its construction, allows such refuse to be inoculated with aninoculant containing beneficial bacteria during the process of particlesize reduction.

An additional object of the present invention is to provide a two-stageparticle size reduction apparatus in which the second stage reduction isenabled to proceed more economically and efficiently by theinterposition of metering means between the two stages for classifyingthe discharge from the first stage according to particle size beforesuch discharge is introduced to the second stage.

An additional object of the present invention is to provide apulverizing device which may 'be more efficiently utilized forpulverizing a mass of heterogeneous materials of widely varying size andquality.

An additional object of the present invention is to provide a compact,ruggedly constructed system for effectively reducing the averageparticle size of raw municipal refuse.

An additional object of the present invention is to provide a system forpulverizing and grinding a mass of heterogeneous materials, which systemis relatively economical to construct, is characterized by the absenceof complicated and delicate elements, and is characterized by a long andtrouble-free operating life.

Other objects and advantages of the invention will be evident from thefollowing detailed description when read in conjunction with theaccompanying drawings which illustrate my invention.

In the drawings:

FIGURE 1 is a schematic plan view of the comininuting system of thepresent invention.

FIGURE 2 is an enlarged schematic view illustrating the relationship ofthe metering device of the invention to the chain grinder which isutilized to effect the final particle size reduction.

FIGURE 3 is a sectional view taken along line 33 of FIG. 1.

FIGURE 4 is a sectional view taken along line 44 of FIG. 3.

FIGURE 5 is a sectional view taken along line 5-5 of FIG. 1.

FIGURE 6 is a detail View illustrating the bladed plates secured to theinside of the pulverizing drum for the purpose of effecting an initialpulverization of waste material.

FIGURE 7 is a detail view illustrating the pulverizing cusped wheelsutilized in a modified embodiment of the present invention.

Referring now to the drawings in detail, and particularly to FIG. 1, theinitial comminution or particle size reduction of the raw refusematerial is accomplished in a large, horizontal drum 10. The drum 10 ismounted upon a suitable drive mechanism 11 for rotation about ahorizontal axis. A suitable inlet conveyor 12 is utilized to move theraw refuse into the intake end 14 of the drum 10. As shown in FIGS. 1and 5, the intake end portion 14 of the drum 10 is of enlarged diameterin order to receive the discharge end of the conveyor 12, and to allowthe drum to be utilized at full capacity. The enlarged end portion 14 ofthe drum 10 also provides an accommodation for a series of sweep blades16 which are secured in circumferentially spaced relation around theinner periphery of the drum 10. As will also be perceived in referringto FIGS. 1 and 5, the sweep blades 16 are inclined or pitched withrespect to the axis of rotation of the drum 10 so that the blades 16 onthe upwardly moving side of the drum are inclined downwardly toward thedischarge end of the drum whereby material entering the drum from theconveyor 12 will be moved by the sweep blades 16 toward the center ofthe drum. A similar set of sweep blades 18 is located at the dischargeend 20 of the drum 10 and functions to move the pulverized refuse out ofthe drum and into a metering device, designated generally by referencecharacter 22. Thus, the sweep blades 16 and 18 function to positivelyfeed the raw refuse toward the center of the pulverizing drum 10 fromthe intake end 14 thereof, and to discharge pulverized refuse from thedischarge end 20 of the drum, respectively.

In a preferred embodiment of the invention, pulverization of the refusein the drum 10 is accomplished by means of a series of bladed members.The bladed members are triangular-shaped plates 24 having each of thethree edges or sides 24a, 24b and 24a of each plate sharpened to acutting edge as shown in FIG. 6. The plates 24 are preferablyequilateral in configuration, and are provided with holes adjacent eachvertex to allow the plates to be bolted to the inner periphery of thedrum It with one of the vertices projecting inwardly toward the axis ofrotation of the drum. When plates of this construction are utilized, theplates may be easily shifted to present a new cutting edge for contactwith the refuse when the edges defining the radially projecting vertexbecome dulled. The plates 24 are arranged in rows which extendlongitudinally of the drum 10 and each of the rows is preferablyspirally or helically arranged with 4 respect to the axis of rotation ofthe drum as best shown in FIG. 1. The manner in which the bladed plates24 accomplish pulverization of the refuse is more fully described below.

The metering device 22 is of generally annular configuration and issecured to the discharge end 20 of the drum 10 for rotation therewith.The metering device 22 comprises a plurality of elongated, flat paddles25 secured between a pair of annular end plates 26. One of the endplates 26 is coaxially secured to the drum 10 at its discharge end 20 inthe manner most clearly illustrated in FIG. 4. The second end plate 26is spaced from the first end plate 26 along the axis of rotation of thedrum 10 by a distance corresponding to the length of the paddles 25.Each of the paddles 25 is secured between the end plates 26 at an acuteangle with respect to the peripheries of the end plates. The angles madeby the paddles 25 with the peripheries of the end plates 26 areidentical so that the distance between the outer edges of adjacentpaddles 25 is greater than the distance between the inner edges ofadjacent paddles. This construction prevents pulverized material frombecoming packed between the paddles 25 and therefore becoming difiicultto discharge from the metering device 22 in the manner hereinafterexplained.

A plurality of spaced, annular bars 28 are disposed around the innerperiphery of the metering device 22 and are secured to the inner edgesof the flat paddles 25. It will further be noted that the bars 28 aredisposed concentrically with respect to the axis of rotation of the drum10, and that they are spaced from each other by distances which increaseas the distance of adjacent bars from the discharge end 20 of the drum10 increases. Stated differently, the spacing of the annular bars 28 issuch that pulverized refuse discharged from the drum 10 will beclassified according to particle size as it moves through the meteringdevice 22 and is discharged between the paddles 25. i

An arcuate, semicylindrical housing 30 is positloned beneath themetering device 22 in juxtaposition to the outer edges of the paddles25. As shown in FIG. 3, the housing 30 is located with one of itslongitudinal edges 30a positioned slightly above the horizontal planeoccupied by the axis of rotation of the drum 10, and its otherlongitudinal edge 3% located below said plane on the other side of themetering device 22. Thus, when the drum 1t) and metering device 22 arerotated in the direction indicated by the arrows in FIGS. 3 and 5, thehousing 30 cooperates with the paddles 25 of the metering device 22 tomove refuse through an arcuate path from the longitudinal edge 30a tothe longitudinal edge Stlb.

The refuse is laterally discharged from the metering device 22 over thelongitudinal edge 30b of the housing 30 and enters a suitable grindingdevice 32 extending alongside the pulverizing drum and metering device.In the preferred embodiment of the invention illustrated by theaccompanying drawings, the grinding device 32 employed is a chaingrinder of the type disclosed in my U.S. Patent 2,965,320 issuedDecember 20, 1960. The chain grinder 32 is characterized by a pluralityof free-swinging chains 34 attached at one of their ends to a rotatingshaft 36 which extends coaxially through the center of a generallycylindrical housing 38. In referring to FIGS. 2 and 3 of the drawings,it will be observed that the intake opening 40 of the housing 38 of thechain grinder 32 is aligned with the longitudinal edge 3% of the arcuatehousing 30 to receive pulverized refuse discharged laterally from themetering device 22. It will also be noted that the larger particles ofpulverized refuse discharged from the metering device 22 enter one endof the chain grinder 32 and travel through the entire length of thechain grinder, whereas relatively smaller particles enter the chaingrinder intermediate its length and travel through only a portion of thegrinder. The ground refuse is discharged through a discharge duct 42located at the opposite end of the chain grinder 32 from the intakeopening 40.

In order to assure that none of the particles of pulverized refuse arecarried upwardly past the edge 30b of arcuate housing 30 by the paddles25, the paddles are inclined so as to make an angle of approximately 30degrees with the vertical at the instant their outer edges move past theedge 301). Thus, refuse will gravitate downwardly of the upper surfaceof the paddles 25 and into the chain grinder 32 when the paddles moveupwardly past the longitudinal edge 30b of arcuate housing 30.

Some extremely difiic-ultly grindable materials may not be sufficientlyreduced in size by the pulverizing device to pass through the annularbars 28 and between the paddles 25 of the metering device 22. Suchmaterials are moved axially through the metering device 22 and onto adischarge chute 44. From the discharge chute 44, this bulky overagematerial gravitates onto an overage conveyor 46 which extendstransversely with respect to the metering device 22 and pulverizing drum10. The overage conveyor 46 may be a simple belt-type conveyor, andfunctions to convey the overage material to a second conveyor 48 whichextends alongside the drum and metering device 22. A chute 50 extendsover the conveyor 48 and facilitates the addition of composted materialrich in beneficial bacteria to the overage material for purposes ofpreinoculation. The inoculated overage is then transmitted by a thirdconveyor 52 to the intake conveyor 12 for recycling through thepulverizing drum 10.

Operation To summarize the operation of the comminuting system of thepresent invention, a mixture of heterogeneous materials, such as rawmunicipal refuse, is fed into the pulverizing drum 10 by the intakeconveyor 12. The mass of refuse will contain such widely varyingmaterials as metal plates, chunks of glass, tree limbs, bedsprings,cardboard boxes and garbage. These materials are positively fed into thecentral portion of the pulverizing drum 10 by the sweep blades 16located at the intake end 14 of the drum. The action of the sweep blades16 is such that the refuse material is picked up on the blades and thenis allowed to gravitate downwardly toward the interior of the drum onthe upper surface of the blades located on the upwardly moving side ofthe rotating drum.

As the waste material is moved toward the center of the pulverizing drum10, it is subjected to the action of the bladed plates 24. The rate ofrotation of the drum 10 is relatively slow so that materials becomeimpaled upon the plates 24 at the bottom of the drum and are carriedupwardly by the plates through an arc of rotation corresponding to aboutone third of the circumference of the drum 10. The weight of the refusethen causes it to become disengaged from the blades upon which it isimpaled, and it gravitates downwardly upon those blades then at thebottom portion of the drum. The sharp, pointed blades thus pierce andcut into the waste material gravitated downwardly. Moreover, thatmaterial which has been resting upon the blades in the lower por tion ofthe drum is subjected to the impact of the downwardly falling portion ofmaterial and is forced further upon the cutting edges of the blades.Also, shear forces of considerable magnitude are established in the massof the refuse by the constant shifting induced by the rotating drum. Thepulverizing action occurring inside the drum 10 may therefore beproperly described as a grinding, piercing and cutting action.

As the raw refuse material continues to be introduced at the inlet end14 of the drum 1%), the pulverized refuse in the drum is constantlymoved toward the discharge end 20 thereof. When the pulverized refusereaches the discharge end 20 of the drum 10, it is picked up by thesweep blades 18 and moved out of the discharge end of 6 the drum by anaction identical to that attributable to the sweep blades 16 located atthe inlet end of the drum.

Pulverized refuse discharged from the drum 10 is received by themetering device 22. The purpose of the metering device 22 is tosegregate or classify the discharged pulverized material according toparticle size. As the metering device 22 is rotated, the pulverizedmaterial inside the metering device will gravitate outwardly through theannular bars 28 and the paddles 25. The varying spacing between theannular bars 28 (illustrated most clearly in FIG. 4) causes thepulverized material to be selectively classified according to particlesize with smaller particles of material being passed between the paddles25 at a point closer to the drum 10 than larger particles of material.Stated differently, the varying sizes of the openings between theannular bars 28 provide for a grading of the material discharged fromthe pulverizing drum 10, such that the finer materials are the firstwhich are allowed to fall between the paddles 25, and the larger sizesof particles fall between the paddles 25 at progressively increasingdistances from the discharge end 20 of the pulverizing drum 10. Thosematerials which have not been sufiiciently reduced in size by thepulverizing action of the pulverizing drum 10 to pass through the bars28 and paddles 25 pass instead through the metering device 22 in anaxial direction and are discharged through the discharge chute 44 ontothe overage conveyor 46.

The graded material which gravitates downwardly through the paddles 25of the metering device 22 bears against the arcuate housing 30 and isthus moved by the action of the paddles 25 through an arcuate path tothe edge 30b of the housing 30. At the edge 3% of the housing 30, thepaddles 25 push the pulverized material into the intake opening 40 ofthe chain grinder 32 where a further reduction in particle size iseffected.

In referring to FIG. 2, it will be perceived that the orientation of thechain grinder 32 with respect to the metering device 22 is such that thefiner particles discharged from the metering device enter the grinder ata point which is closer to the discharge chute 42 of the grinder thanthe point of entry of the relatively larger pulverized materials. Thus,the smaller particles of pulverized material are caused to travel ashorter distance through the chain grinder 32, and the larger particlesof pulverized material must pass through a longer path of travel throughthe chain grinder. The latter materials are therefore subjected to anincreased period of grinding and the load on the chain grinder isreduced to a minimum. In order to assure that none of the pulverizedmaterial is carried upwardly past the inlet 40 of the chain grinder 32by the paddles 25, each of the paddles is inclined to form an angle ofapproximately 30 degrees with the vertical at the instant when thepaddle is opposite the longitudinal edge 30b of the arcuate housing 30.This relationship is illustrated in FIG. 3 of the drawings.

The large, bulky overage materials which have passed axially through themetering device 22 and come to rest upon the overage conveyor 46 arerecycled to the inlet conveyor 12 by means of conveyors 48 and 52. Whilethe overage material is on the conveyor 48, a portion of the refusematerial which has been composted by operations occurring subsequent tothe comminuting operation of the present invention is added to theoverage material by means of a chute 50 extending into juxtaposition tothe conveyor 48. This composted material is highly enriched inbeneficial bacteria and spores, and its addition to the overage materialfrom the pulverizing device accomplishes a valuable preinoculation ofthe overage material and the raw refuse with which it is mixed upon theinlet conveyor 12. The composted material which is added to the overagemay conveniently be overage material derived from a final screening ofthe final compost product. On the other hand, it may, in some instances,be desirable to add bacteria-rich sewage to the overage to effect thepreinoculation. It may also be desirable to use a plurality of therotatably mounted cusped wheels 56 (shown in FIG. 7) for pulverizing therefuse instead of the bladed plates 24. The cusped wheels 56 arejournaled on shafts 58 which are in turn journaled in plates 60 securedto the inner Wall of the drum 10. A series of cusps 62 are securedaround the outer periphery of each of the wheels 56 so that as the wheelturns randomly, all of the cusps are exposed to equal wear.

From the foregoing description, it will be apparent that the comminutingsystem of the present invention provides a system which is peculiarly,though not exclusively, adapted to the preparation of raw municipalrefuse for subsequent composting by bacteriological decomposition. Theapparatus is relatively compact by virtue of the arrangement of theseveral components, and yet is capable of high-capacity operation. Thetwo-stage particle size reduction operation permits a mixture of widelydifiering materials to be greatly reduced in average particle size andto be preinoculated preparatory to subsequent subjection to thedecomposting action of bacteria.

Although this invention has been described with a certain degree ofspecificity, it is manifest that many changes may be made in the detailsof construction and the arrangement of components without departing fromthe spirit and scope of this disclosure. Accordingly, this inventionshould be considered as limited only by the scope of the appendedclaims.

I claim:

1. A system for reducing the average particle size of a mixture ofheterogeneous materials comprising the combination of a rotatablymounted, horizontal drum having pulverizing means secured to theinternal wall thereof for eifecting an initial particle size reductionof said materials; metering means at one end of said drum forclassifying pulverized material discharged from said drum according toparticle size; and a grinding device positioned alongside saidhorizontal drum and metering device for receiving classified materialdischarged laterally in a generally horizontal direction from saidmetering device, said grinding device cooperating with said meteringmeans to subject the material of relatively larger particle sizedischarged from said drum to more extensive grinding than the materialof relatively smaller particle size which is discharged from said drum.

2. A particle size reducing system as claimed in claim 1 wherein saidgrinding device comprises a chain grinder, and wherein said meteringmeans comprises a substantially annular plate coaxially secured to thedischarge end of said drum for rotation with said drum; a second,substantially annular plate axially spaced from said first plate; aplurality of flat, axially extending, elongated paddles rigidly securedbetween said plates and circumferenti-ally spaced from each other aroundsaid plates, said paddles being secured to said plates with their flatsides inclined at identical acute angles to the circumferences of saidannular plates; and a plurality of annular bars secured to the inneredges of said paddles in coaxial relation to the axis of rotation ofsaid drum with said bars being spaced increasing distances from eachother along said axis of rotation from said first plate to said secondplate; and wherein said system is further characterized to include anarcuate, semi-cylindrical housing immediately below said metering meansand originating with one of its longitudinal edges located on one sideof said metering means and above a horizontal plane containing the axisof rotation of said drum, and terminating with one of its longitudinaledges located below said plane on the other side of said metering means,said arcuate housing cooperating with the paddles of said metering meansto move said discharged material through an arcuate path from the originto the terminus of said housing for discharge therefrom.

3. A particle size reducing system as claimed in claim 1 and furthercharacterized to include means for recycling to .said drum overagematerial of a particle size too large to be discharged to said grindingdevice by said metering means.

4. A particle size reducing system as claimed in claim 3 wherein saidrecycling means comprises a conveyor system for receiving said largeparticles from one end of said metering means and returning saidparticles to the intake end of said drum.

5. A particle size reducing system as claimed in claim 3 and furthercharacterized to include means for inoculating said recycled, overagematerial with a material containing beneficial bacteria and spores priorto the reintroduction of said overage material to said drum.

6. A particle size reducing system as claimed in claim 1 wherein thediameter of said drum is enlarged at its end opposite said meteringmeans to facilitate the introduction to said drum of the mixture to bepulverized; and further characterized to include means secured to theinternal wall of said drum adjacent the ends thereof for positivelyfeeding and discharging the mixture when said drum is rotated.

7. A particle size reducing system as claimed in claim 6 wherein saidfeeding means comprises a plurality of elongated sweep blades secured tothe inner periphery of said drum in circumferentially spaced relationand pitched with respect to the longitudinal axis of said drum so thatthe blades on the upwardly moving side of said drum are inclineddownwardly toward the discharge end of said drum whereby material in thebottom of said drum will be moved by said blades toward the center ofsaid drum before pulverization and out of said drum after pulverization.

8. A pulverizing device for reducing the average particle size of raw,heterogeneous, unclassified refuse material comprising a horizontal,rotatably mounted drum; a plurality of elongated sweep blades secured tothe inner periphery of said drum adjacent the inlet and discharge endsthereof in circumferentially spaced relation and pitched with respect tothe longitudinal axis of said drum so that the blades on the upwardlymoving side of said drum are inclined downwardly toward the dischargeend of said drum whereby material at the bottom of said drum will bemoved by said blades toward the center of said drum beforepulverization, and toward the discharge end of said drum afterpulverization; cutting, incising means comprising a plurality of axiallyextending rows of substantially equilateral triangular blades secured tothe inner periphery of said drum between the inlet and discharge endsthereof, said equilateral triangular blades each having one of theirvertices projecting radially toward the axis of rotation of said drum,and further having each of the three sides thereof sharpened to acutting edge; and means for detachably securing said blades to said drumwith one side of each of said blades coincident with a chord of saiddrum whereby said equilateral triangular blades may each be detachedfrom said drum and rotated in the same plane through so as to presentnew cutting edges and a new pointed vertex for contact with said raw,heterogeneous, unclassified refuse material when said detachablesecuring means is used to secure a second side of each of said blades tosaid drum coincident with the same chord thereof.

9. A pulverizing device for reducing the average particle size of raw,heterogeneous, unclassified refuse material comprising a horizontal,rotatably mounted drum; cutting, incising means in said drum forpulverizing material introduced to the interior of said drum; sweepblades secured to the inner periphery of said drum adjacent the inletand discharge ends thereof in circumferentially spaced relation andpitched with respect to the longitudinal axis of said drum so that theblades on the upwardly moving side of said drum are inclined downwardlytoward the discharge end of said drum whereby material from the bottomof said drum Will be moved by said blades toward the center of said drumbefore pulverization and toward the discharge end of said drum afterpulverization; a first substantially annular plate secured to thedischarge end of said drum for rotation with said drum; a secondsubstantially annular plate axially spaced with said first plate; aplurality of flat, axially extending, elongated'paddles rigidly securedbetween said plates and circumferentially spaced from each other aroundsaid plates; said paddles being secured to said plates with their fiatsides inclined at acute, identical angles to the circumferences of saidannular plates; and a plurality of annular bars secured to the inneredge of said paddles in coaxial relation to the axis of rotation of saiddrum with said bars being spaced increasing distances from each otheralong said axis of rotation from said first plate to said second platewhereby pulverized material of relatively small particle size is allowedto pass radially outward through said paddles relatively closer to saiddrum than pulverized material of relatively larger particle size.

10. A pulverizing device as claimed in claim 9 and further characterizedto include an arcuate housing immediately below said metering means andoriginating on one side of said metering means above a horizontal planecontaining the axis of rotation of said drum and terminating on theother side of said metering means below said horizontal plane, saidarcuate housing cooperating with said paddles to move said dischargedmaterial through an arcuate path from the origin to the terminus of saidhousing for discharge therefrom.

11. A pulverizing device as claimed in claim 10 wherein each of saidpaddles extends downwardly from said annular bars at an angle ofapproximately 30 degrees to the vertical when said paddle is injuxtaposition to the terminus of said housing whereby pulverizedmaterial will gravitate from the flat upper surface of said paddles pastsaid terminus in being discharged from said arcuate housing.

12. A pulverizing device for reducing the average particle size of raw,heterogeneous, unclassified refuse material comprising a horizontal,rotatably mounted drum; a plurality of elongated sweep blades secured tothe inner periphery of said drum adjacent the inlet and discharge endsthereof in circumferentially spaced relation and pitched with respect tothe longitudinal axis of said drum such that the blades on the upwardlymoving side of said drum are inclined downwardly toward the dischargeend of said drum whereby material from the bottom of said drum will bemoved by said blades toward the center of said drum before pulverizationand toward the discharge end of said drum after pulverization; aplurality of axially extending rows of wheels rotatably secured to theinner periphery of said drum between said inlet and discharge ends ofsaid drum; and a plurality of sharp, pointed cusps secured incircumferentially spaced relation around the periphery of each of saidwheels.

13. A pulverizing device for reducing the average particle size of raw,heterogeneous, unclassified refuse material comprising a horizontal,rotatably mounted drum; cutting, incising means in said drum forpulverizing material introduced to the interior of said drum; aplurality of elongated sweep blades secured to the inner periphery ofsaid drum adjacent the inlet and discharge ends thereof incircumferentially spaced relation and pitched with respect to thelongitudinal axis of said drum so that the blades on the upwardly movingside of said drum are inclined downwardly toward the discharge end ofsaid drum whereby material from the bottom of said drum will be moved bysaid blades toward the center of said drum before pulverization andtoward the dis-charge end of said drum after pulverization; a generallycylindrical member having a plurality of axially extending openingstherein secured to the discharge end of said drum for receivingpulverized material from said drum, the openings in said cylindricalmember being graduated in areal size from the end of said cylindricalmember adjacent the discharge end of said drum to the oppos te end ofsaid generally cylindrical member with the axially extending openings ofsmallest areal size adjacent the discharge end of said drum, and theaxially extending openings of greatest areal size adjacent the end ofsaid cylindrical member opposite the discharge end of said drum.

References Cited by the Examiner UNITED STATES PATENTS 813,903 2/1906Lin-dhard 241-78 843,466 2/1907 Krickbaurn 241-181 2,213,713 9/1940Maxson 241181 XR 2,523,034 9/1950 Lively 241-188 XR 2,721,035 10/1955Lankford et al. 2,871,510 2/1959 Sackett 23-259.1 XR 2,948,593 8/1960Larson 23-259.1 2,965,320 12/1960 Pierson 241185 2,994,592 8/1961 Scovelet a1 23259.1

FOREIGN PATENTS 1,224,230 6/1960 France.

727 1884. Great Britain. 457,458 3/ 1950 Italy.

MORRIS O. WOLK, Primary Examiner.

MICHAEL A. BRINDISI, Examiner.

1. A SYSTEM FOR REDUCING THE AVERAGE PARTICLE SIZE OF A MIXTURE OFHETEROGENEOUS MATERIALS COMPRISING THE COMBINATION OF A ROTATABLYMOUNTED, HORIZONTAL DRUM HAVING PULVERIZING MEANS SECURED TO THEINTERNAL WALL THEREOF FOR EFFECTING AN INITIAL PARTICLE SIZE REDUCTIONOF SAID MATERIALS; METERING MEANS AT ONE END OF SAID DRUM FORCLASSIFYING PULVERIZED MATERIAL DISCHARGED FROM SAID DRUM ACCORDING TOPARTICLE SIZE; AND A GRINDING DEVICE POSITIONED ALONGSIDE SAID HRIZONTALDRUM AND METERING DEVICE FOR RECEIVING CLASSIFIED MATERIAL DISCHARGEDLATERALLY IN A GENERALLY HORIZONTAL DIRECTION FROM SAID METERING DEVICE,SAID GRINDING DEVICE COOPERATING WITH SAID METERING MEANS TO SUBJECT THEMATERIAL OF RELATIVELY LARGER PARTICLE SIZE DISCHARGED FROM SAID DRUM TOMORE EXTENSIVE GRINDING THAN THE MATERIAL OF RELATIVELY SMALLER PARTICLESIZE WHICH IS DISCHARGED FROM SAID DRUM.